The present invention relates to an arrangement for lining blast furnaces.
It is well known that a blast furnace has an inner lining of refractory material which is to be repaired or replaced from time to time as the old refractory lining becomes worn out. For this purpose, it is already known in the prior art to erect a scaffolding in the interior of the blast furnace which is generally similar to such scaffoldings which are used in the construction industry. Such conventional scaffolding includes a plurality of supporting and connecting elements, such as beams and struts, and a plurality of working platforms which are supported on the support and connecting elements.
A multitude of problems is encountered when such conventional scaffolding of a stationary nature is used for the purpose of removing the worn-out lining of refractory material and replacing the same by a new lining. First of all, it is well known that the shaft or stack section of the blast furnace, on the one hand, and the bosh section, on the other hand, has generally frustoconical configurations with the imaginary frusto-cones converging from an imaginary basis. Thus, the transverse inner dimensions of the blast furnace vary in dependence on the elevation within the blast furnace. The conventional stationary scaffolding must take this variation in the inner dimensions of the blast furnace into account. For this purpose, the stationary scaffolding is equipped with cantilevered support portions at different levels of the scaffolding, which cantilevered support portions extends all the way toward the inner surface of the refractory lining. In this manner the varying inner dimensions of the blast furnace are taken into consideration in a stepwise manner.
The stationary scaffolding of the prior art surrounds a shaft for an elevator which lifts the lining material, such as refractory bricks, needed for the construction of the refractory lining, to the different levels of the scaffolding. The refractory material is usually introduced into the interior of the blast furnace through an opening which is provided in the jacket of the hearth, being supported on pallets.
In view of the fact that blast furnaces have heights of up to 40 meters or more, the scaffoldings used for lining the interior of such blast furnaces must be constructed as a grid of the supporting and connecting elements which includes a multitude of such elements at relatively small spacing from one another, which elements must be anchored at many locations. As a result of this tight-grid construction of the scaffoldings, the interior space of the blast furnace, which is relatively small as it is, is further reduced.
Another disadvantage of this prior-art approach is that the erection of the stationary scaffolding consumes an inordinate amount of time, such as several days, and must be performed with a high degree of skill. Similar considerations are also valid for dismounting the scaffolding subsequent to the construction or reconstruction of the refractory lining.
A further disadvantage of the stationary scaffolding is to be seen in the fact that, prior to the construction of the new refractory linings, the old and worn-out refractory lining must be removed all the way to the blast furnace jacket. The removed old refractory lining ideally falls into the hearth of the blast furnace and is removed therefrom through a lateral opening, which is later closed, but which is used before such closing also for introduction of the new refractory material into the interior of the blast furnace. In practice, however, the larger part of the removed old refractory lining falls into the scaffolding and onto the platform located at various levels thereof. This, of course, is very disadvantageous, particularly in view of the danger that the scaffolding may be damaged by the impacts of the old lining particles thereupon. On the other hand, bulky parts of such old refractory material may become lodged between the inner wall of the blast furnace and the various supporting and connecting elements of the scaffolding and must be removed therefrom, in a very difficult and time-consuming operation, by the personnel working on the scaffolding. As a result of these disadvantages and of the difficult working conditions attendant thereto, a time span of several weeks is generally needed for removal of the old, worn-out refractory lining, whereas approximately the same time span is needed for constructing the new refractory lining. This, of course, is in addition to the time period which is needed for the mounting and dismounting of the scaffolding, which time period may also take up to several weeks.